MSH-6: extending the reliability of immunohistochemistry as a screening tool in Muir-Torre syndrome

A retrospective cohort study of genetic referral and diagnosis of lynch syndrome in patients with cutaneous sebaceous lesions

Immunohistochemistry (IHC) of cutaneous sebaceous lesions (SL) can be used to screen patients for Lynch syndrome (LS). There is little data on rates of genetic referral and outcomes of genetic testing for patients with SL. This single-center retrospective study characterizes 400 + patients with SL, including IHC results, genetics referrals, and outcomes of genetic testing. Retrospective chart reviews were performed for patients with a pathology-confirmed diagnosis of SL at the University of Michigan between January 2009 and December 2019. 447 patients with 473 SL were identified. Excluding 20 patients with known LS, IHC was conducted in 173 (41%) patients. 92/173 (53%) patients had abnormal results. 69 of these 92 (75%) patients were referred to genetics. 32 additional patients were referred with normal IHC (n = 22) or without IHC (n = 10). Of 101 patients referred, 65 (64%) were seen and 47 (47%) completed genetic testing. 7/47 (15%) had pathogenic variants associated with LS, six with concordant abnormal IHC and one without IHC. Cancer genetics referral of patients with SL, particularly for lesions with abnormal IHC, yields a significant rate of LS diagnosis. Providers should consider genetics referral for patients with SL.

Microsatellite Instability in Near East Sebaceous Neoplasms: Toward Improved Prediction

Sebaceous neoplasms (SN) comprise a heterogeneous spectrum of tumors with different biological behaviors. In the Near-East Region (NER), microsatellite instability (MSI) in SN's development, and its correlation with the clinicopathologic features of tumors is not well elucidated. A cohort of 225 SN patients (40 benign SNs and 185 sebaceous carcinomas) from the NER was retrospectively reviewed. Clinical variables and available follow-up information were recorded. MSI proteins (MLH1, MSH2, MSH6, and PMS2) as well as P53, P16, EMA, CD8, and PDL-1 expressions were examined by immunohistochemistry. Detection of human papilloma virus was determined by polymerase chain reaction. Microscopic features such as mitotic count and tumor-infiltrating lymphocytes were documented. A minority of SNs from benign (n=2) or malignant (n=3) tumors in the NER exhibit MSI (2.2%). MSI is exclusively found in patients with extraocular lesions (back, n=5) and presented a poor outcome. Among these, PMS2 protein was mostly lost (average=80%, n=4). SN with MSI exhibited a significant increase in p53 expression, (average=62.10%, P=0.002). There was no significant correlation between MSI status and any of the following: PD-L1, CD8, p16, and human papilloma virus infection. Microscopically, SN with MSI show significantly higher mitotic count, cystic changes and increased tumor-infiltrating lymphocytes. MSI is rarely found in NER's SN. When detected, it is exclusively in extraocular SNs with minimal predicative microscopic features and worse outcome.

When to Consider Lynch Syndrome in Non-Colon and Non-Endometrial Malignancies

Lynch syndrome (LS) is a common genetic syndrome characterized by pathogenic mutations of DNA mismatch repair genes resulting in a hereditary predisposition to cancer. While typically associated with colonic and endometrial cancer, LS additionally influences the development of many other malignancies. The Amsterdam II and Revised Bethesda Guidelines are the established clinical criteria for diagnosing LS. These guidelines are based on the most general characteristics of LS and do not address specific characteristics of the less commonly LS-associated malignancies. For individuals that present initially with a non-colon and non-endometrial malignancy, recommendations and guidelines on when to consider screening for LS are limited. Therefore, it is essential that clinicians are familiar with distinct LS-associated patient- and tumor-specific characteristics, especially of the less common LS-associated cancers, so that LS's diagnosis is not missed. In this review article, we focus on extra-colonic and extra-endometrial LS-associated cancers, paying particular attention to any established or currently investigated cancer features that help raise suspicion for LS and potentially lead to its earlier diagnosis. This review will also discuss current guidelines specific to each LS-associated malignancy.

Case Report: A Frameshift Mutation in MSH2 Exon 2 in a Kidney Recipient With Muir-Torre Syndrome

Muir-Torre syndrome (MTS), a rare subtype of Lynch syndrome, is mostly autosomal dominant, which is caused by germline mutations in DNA mismatch repair (MMR) genes, the resulting microsatellite instability (MSI) of which increases the risk of developing sebaceous and other visceral tumors. Several reports have showed an association between immunosuppressive agents and the progression of latent MTS. In this report, we described a 41-year-old man with a history of kidney transplantation, having a rapid growth of the nodule on the anterior chest under immunosuppressive therapy, which was histologically proved to be sebaceous carcinoma. Systemic evaluation for visceral malignancies revealed sigmoid adenocarcinoma. These findings were consistent with the clinical diagnosis of MTS. Histological findings showed an absence of MMR proteins, including MSH2 and MSH6 both in the sebaceous carcinoma and sigmoid adenocarcinoma on immunohistochemical (IHC) analysis. A frame-shift mutation of c.229_230delAG (p. Ser77fs) in the MSH2 exon 2 in the lesion was detected by next-generation sequencing (NGS) analysis. This case report not only reveals a new site of MSH2 mutation in this family of East Asian descent but also highlights the importance of adequate diagnosis for Muir-Torre syndrome, as well as further prevention of the development of latent visceral tumors in kidney transplant recipients.

Comparison of adipophilin and recently introduced PReferentially expressed Antigen in MElanoma immunohistochemistry in the assessment of sebaceous neoplasms: A pilot study

BACKGROUND

We and others have noticed consistent staining of sebaceous glands with PReferentially expressed Antigen in MElanoma (PRAME). We aimed to determine whether PRAME was as sensitive, specific, and interpretable as adipophilin for distinguishing sebaceous neoplasms (SNs) from other neoplasms.

METHODS

Twenty SNs and 32 control cases were stained for PRAME and adipophilin. Extent of staining was scored as follows: 0, no staining; 1, <5% positivity; 2, 5% to 50% positivity; and 3, >50% positivity. Intensity was scored as negative, weak, moderate, or strong. A composite score was determined by adding the scores for extent and intensity.

RESULTS

PRAME had positive composite scores in all 20 SNs in the more differentiated areas, whereas adipophilin had positive composite scores in 19/20 cases. PRAME showed positivity in the basaloid cells in 15/16 cases, whereas adipophilin was positive in 14. Among controls, PRAME and adipophilin had positive composite scores in 3/32 cases and 6/32 cases, respectively.

CONCLUSIONS

PRAME and adipophilin are comparable in terms of distribution and intensity for staining sebocytes. In the basaloid cells, PRAME expression is often more diffuse and easier to detect than adipophilin. In comparing the SNs to the controls, PRAME was more sensitive and more specific than adipophilin. PRAME could be used as an additional marker of sebaceous differentiation in everyday practice.

Update on the pathology, genetics and somatic landscape of sebaceous tumours

Cutaneous sebaceous neoplasms show a predilection for the head and neck area of adults and include tumours with benign behaviour, sebaceous adenoma and sebaceoma, and sebaceous carcinoma with potential for an aggressive disease course at the malignant end of the spectrum. The majority of tumours are solitary and sporadic, but a subset of tumours may be associated with Lynch syndrome, also known as hereditary non-polyposis colon cancer (HNPCC) and previously referred to as Muir-Torre syndrome (now known to be part of Lynch syndrome). This review provides an overview of the clinical and histological features of cutaneous sebaceous neoplasia with an emphasis on differentiating features and differential diagnosis. It also offers insights into the recently described molecular pathways involved in the development of sebaceous tumours and their association with Lynch syndrome.

Immunohistochemistry as a Genetic Surrogate in Dermatopathology: Pearls and Pitfalls

Immunohistochemistry (IHC) is routinely performed in most laboratories, and other than purchase of commercially available antibodies, requires no additional equipment or reagents. As such, IHC is an accessible and relatively inexpensive test and one that can be performed quite quickly. This is in sharp contrast to genomic or mutational testing methodologies that are routinely "send out" tests as they require specialized equipment and reagents as well as individuals with expertise in the performance of the tests and analysis of the results, resulting in a prolonged turn-round-time and enhanced associated costs. However, many open questions remain in a rapidly changing therapeutic and scientific landscape with most obvious one being what exactly is the utility of "good old fashioned" IHC in the age of targeted therapy? For molecular applications, is a negative immunohistochemical result enough as a stand-alone diagnostic or predictive product? Is a positive immunohistochemical result perhaps more suitable for a role in screening for molecular alterations rather than a definitive testing modality? This review is an attempt to answer those very questions. We elucidate the broad range of entities in which IHC is currently used as a molecular surrogate and underscore pearls and pitfalls associated with each. Special attention is given to entities for which targeted therapies are currently available and to entities in which molecular data is of clinical utility as a prognosticator.

Muir-Torre Syndrome: A Case Report in a Woman Without Personal Cancer History

We report a case of a 68-year-old white woman presenting with 5 sebaceous neoplasms, ranging from sebaceous adenoma to sebaceoma on histopathology. Despite the lack of a personal cancer history, her multiple sebaceous neoplasms and a paternal history of colon cancer prompted testing her sebaceous adenomas for microsatellite instability (MSI) by immunohistochemistry. The results showed retained nuclear expressions of MLH1 and PMS2 while MSH2 and MSH6 proteins were absent. The tumor infiltrating lymphocytes expressed both MSH2 and MSH6, providing reliable internal positive controls. Having a high probability for MSI, she was found to be heterozygous for a germline point mutation in MSH2 gene, where a pathologic variant, c.1165C > T (p.Arg389*), determined by sequencing confirmed Muir-Torre syndrome (MTS). On further genetic counseling recommendations, one of her 2 sons was found to have colon cancer in the context of his MTS. In this article, we highlight and review the implications of MSI testing by both immunohistochemistry and sequencing as they relate to confirming the diagnosis of a suspected case of MTS.

Review of the current medical literature and assessment of current utilization patterns regarding mismatch repair protein immunohistochemistry in cutaneous Muir-Torre syndrome-associated neoplasms

Muir-Torre syndrome is a clinical variant of Lynch syndrome defined by the synchronous or metachronous occurrence of at least one sebaceous neoplasm and at least one Lynch syndrome-related internal cancer. Although screening guidelines for patients with colorectal carcinomas have been established, screening guidelines for cutaneous Muir-Torre associated neoplasms are not currently available. As such, we reviewed the current evidence for the use of MLH1, MSH2, MSH6 and PMS2 immunohistochemistry when cutaneous Muir-Torre associated neoplasms are encountered. We identified weak to moderate support overall for the global use of these assays, with some evidence suggesting a tailored approach using clinical parameters as an adjunct. We also assessed the current utilization patterns of attendees of the American Society of Dermatopathology Annual Meeting (Chicago, 2016). We found that 91% of respondents utilize mismatch repair immunohistochemistry, with the majority utilizing these tests only when requested by the submitting clinician.

Sebaceous Neoplasms

Sebaceous skin tumors are classified into sebaceous adenoma, sebaceoma, and sebaceous carcinoma. An additional group of cystic sebaceous tumors indicate the Muir-Torre syndrome (MTS). Cystic sebaceous tumors are considered as morphologic variants of the 3 main categories. Multilineage adnexal tumors with partly sebaceous differentiation may pose a challenge to categorize. Sebaceous hyperplasia and nevus sebaceus are not considered as true sebaceous tumor entities. Recently, attention has been drawn to morphologic clues of sebaceous differentiation. Immunohistochemistry using the mismatch repair proteins and/or genetic microsatellite instability testing should be performed on sebaceous neoplasms to diagnose MTS as early as possible.

MSH6, Past and Present and Muir-Torre Syndrome-Connecting the Dots

Sebaceous neoplasms such as adenoma, sebaceoma, and carcinoma, although sporadic in their occurrence, are clinically significant because of their association with Muir-Torre syndrome (MTS). MTS is a rare autosomal dominant genodermatosis characterized by the occurrence of sebaceous neoplasms and/or keratoacanthomas and visceral malignancies. MTS is usually the result of germline mutations in the DNA mismatch repair genes MSH2 and, albeit less commonly, MLH1. Although less know, MSH6 is yet another key player. Evidence from Lynch syndrome indicates that pathogenic germline mutations in MSH6 are typically microsatellite stable and have a clinical presentation that differs from that associated with germline mutations in MSH2 and/or MLH1. Given this unique mutator phenotype of MSH6, the primary aim of this review was to underscore the clinical manifestations associated with pathogenic mutations in MSH6 in patients with MTS. As the current clinical and laboratory work-up of MTS is geared toward patients harboring a germline mutation in MSH2 and/or MLH1, an additional aim was to provide a scaffolding for the work-up of a patient presenting with an isolated germline mutation in MSH6.

Muir-Torre syndrome (MTS): An update and approach to diagnosis and management

Muir-Torre syndrome (MTS) is a rare genetic condition that predisposes individuals to skin tumors and visceral malignancies. Because of the potentially aggressive nature of internal malignancies and sebaceous carcinoma, and the tendency to have multiple low-grade visceral cancers, close cancer surveillance is required in individuals and their families with this usually autosomal dominant disorder. Although the majority of MTS is caused by mutations in DNA mismatch repair genes resulting in microsatellite instability, a newly described subtype of MTS does not demonstrate microsatellite instability and may be inherited in an autosomal recessive pattern. In addition, MTS may be unmasked in transplant recipients taking specific immunosuppressant drugs or other immunosuppressed patients. Neoplasms may be subject to immunohistochemistry or both immunohistochemistry and genetic testing to confirm the diagnosis of MTS. Here, we offer an update and an approach to the diagnosis and management of MTS with a particular emphasis on the role of immunohistochemistry and genetic testing.

Mismatch Repair Protein Expression in Fordyce Granules

Fordyce spots are a frequent condition under which sebaceous glands are found in the oral mucosa. There are 2 studies in the literature that have found an association between Fordyce spots and either Muir-Torre syndrome or Lynch syndrome. Despite this, no study on the expression of mismatch repair (MMR) proteins has been performed on biopsies of Fordyce granules. In this study, we intend to study the expression of MMR proteins under Fordyce condition. We investigated 9 cases of Fordyce spots of the oral mucosa from 6 men and 3 women, using immunohistochemistry with antibodies for the MutS protein homolog 6 (MSH6), MutS protein homolog 2 (MSH2), MutL protein homolog 1 (MLH1), and postmeiotic segregation increased 2 (PMS2). All cases showed the preservation of the expression of all markers. Even though a strong association has been demonstrated between Lynch syndrome and Fordyce spots, our study suggests that studying the biopsies of Fordyce condition by immunohistochemistry for MMR proteins might not be necessary.

Importance of universal mismatch repair protein immunohistochemistry in patients with sebaceous neoplasia as an initial screening tool for Muir-Torre syndrome

Muir-Torre syndrome, a Lynch syndrome variant, is characterized by sebaceous neoplasia plus one or more malignancies, typically colon cancer. The significance of DNA mismatch repair (MMR) deficiency detection by immunohistochemistry (IHC) in colorectal carcinomas is well established and is recommended as a screening tool for Lynch syndrome in newly diagnosed colorectal carcinomas. In comparison, literature on IHC application to detect MMR proteins (MLH1, MSH2, MSH6, and PMS2) in sebaceous neoplasia has been less studied and has been derived almost exclusively from tertiary care centers. Herein we describe the largest series to date characterizing MMR deficiency in sebaceous neoplasms, as well as the relative frequencies of each deficiency. Two hundred sixteen consecutive sebaceous neoplasms (216 patients) were analyzed from a community practice setting (133 sebaceous adenomas, 68 sebaceomas, 15 sebaceous carcinomas). One hundred forty-three were MMR deficient (66%), of which 90 were MSH2/MSH6 deficient (63%), 27 MLH1/PMS2 deficient (19%), 22 MSH6 deficient (15%), and 4 PMS2 deficient (3%). MMR deficiency was significantly associated with site, with tumors off of the head and neck more likely to be MMR deficient (specificity 96%). In contrast to prior reports, no significant trend in MMR-deficient versus -nondeficient tumors was seen in age at presentation (median age, 68 versus 66), tumor-infiltrating lymphocytes, or tumor type. Given the low sensitivity of age < 60 years (30%), location off of the head and neck (41%), or presence of tumor-infiltrating lymphocytes (29%) in MMR deficiency detection, IHC screening programs should test all sebaceous neoplasms for MMR deficiency, regardless of their clinicopathological features.

Immunohistochemistry in dermatopathology

CONTEXT

Immunohistochemistry is not a diagnostic test but a highly valuable tool that requires interpretation within a context.

OBJECTIVE

To review the current status and limitations of immunohistochemistry in dermatopathology.

DATA SOURCES

English-language literature published between 1980 and 2014.

CONCLUSIONS

Although immunohistochemistry is rarely completely specific or sensitive, it is an important adjunctive technique in dermatopathology and can be helpful in a series of diagnostic dilemmas.

Sebaceous carcinoma: review of the literature

BACKGROUND

Sebaceous carcinoma is an uncommon adnexal neoplasm with a documented capability for regional and distant metastasis. Traditionally, sebaceous carcinoma has been associated with high rates of recurrence after excision.

OBJECTIVE

To review the current literature on sebaceous carcinoma and detail its epidemiology, pathogenesis, clinical presentation, histopathology, diagnostic workup, treatment, and prognosis.

MATERIALS AND METHODS

Literature review using PubMed search for articles related to sebaceous carcinoma.

RESULTS

Sebaceous carcinoma typically presents as a painless pink or yellow nodule. Diagnosis requires histopathologic examination, and immunohistochemical analysis often assists in the differentiation of sebaceous carcinoma from other benign and malignant skin neoplasms. Sebaceous carcinoma should prompt a workup for Muir-Torre syndrome. Periorbital sebaceous carcinoma has an increased tendency for regional metastasis, although cancer-specific mortality rates are similar among all anatomic locations.

CONCLUSION

Surgery is the preferred treatment for local disease. Limited data suggest that Mohs micrographic surgery may provide superior clinical outcomes, but more research is needed regarding the long-term outcomes. Radiation and systemic chemotherapy are reserved for recurrent or metastatic disease.

Screening for germline mismatch repair mutations following diagnosis of sebaceous neoplasm

IMPORTANCE Sebaceous neoplasms (SNs) define the Muir-Torre syndrome variant of Lynch syndrome (LS), which is associated with increased risk for colon and other cancers necessitating earlier and more frequent screening to reduce morbidity and mortality.Immunohistochemical (IHC) staining for mismatch repair (MMR) proteins in SNs can be used to screen for LS, but data on subsequent germline genetic testing to confirm LS diagnosis are limited.OBJECTIVE To characterize the utility of IHC screening of SNs in identification of germline MMR mutations confirming LS.DESIGN, SETTING, AND PARTICIPANTS Retrospective study at 2 academic cancer centers of 86 adult patients referred for clinical genetics evaluation after diagnosis of SN.MAIN OUTCOMES AND MEASURES Results of tumor IHC testing and germline genetic testing were reviewed to determine positive predictive value and sensitivity of IHC testing in diagnosis of LS. Clinical variables, including age at diagnosis of SN, clinical diagnostic criteria for LS and Muir-Torre syndrome, and family history characteristics were compared between mutation carriers and noncarriers.RESULTS Of 86 patients with SNs, 25 (29%) had germline MMR mutations confirming LS.Among 77 patients with IHC testing on SNs, 38 (49%) had loss of staining of 1 or more MMR proteins and 14 had germline MMR mutations. Immunohistochemical analysis correctly identified 13 of 16 MMR mutation carriers, corresponding to 81% sensitivity. Ten of 12 patients(83%) with more than 1 SN had MMR mutations. Fifty-two percent of MMR mutation carriers did not meet clinical diagnostic criteria for LS, and 11 of 25 (44%) did not meet the clinical definition of Muir-Torre syndrome. CONCLUSIONS AND RELEVANCE Immunohistochemical screening of SNs is effective in identifying patients with germline MMR mutations and can be used as a first-line test when LSis suspected. Abnormal IHC results, including absence of MSH2, are not diagnostic of LS and should be interpreted cautiously in conjunction with family history and germline genetic testing. Use of family history to select patients for IHC screening has substantial limitations,suggesting that universal IHC screening of SNs merits further study. Clinical genetics evaluation is warranted for patients with abnormal IHC test results, normal IHC test results with personal or family history of other LS-associated neoplasms, and/or multiple SNs.

Muir-Torre Syndrome

Muir-Torre syndrome (MTS) is a rare autosomal-dominant genodermatosis characterized by sebaceous neoplasms and one or more visceral malignancies. Sebaceous tumors include sebaceous adenoma and carcinoma, which may be solitary or multiple. Visceral malignancies most often arise in the colorectum and endometrium. Because a subset of patients with phenotypic MTS will have germline mutations in the DNA mismatch repair genes hMSH2 and hMLH1, MTS is considered a phenotypic subtype of Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer syndrome), in which inherited defects in DNA mismatch repair genes result in microsatellite instability. Pathologists have an important role in the early detection and initial diagnosis of MTS: identification of at-risk individuals allows appropriate screening and surveillance for visceral malignancies, thereby reducing morbidity and mortality. Herein, we describe the clinicopathologic features of MTS.

Sebaceous neoplasms and the immunoprofile of mismatch-repair proteins as a screening target for syndromic cases

INTRODUCTION

Muir-Torre syndrome (MTS), a subset of Lynch syndrome, is characterized by concurrent or sequential development of sebaceous neoplasms, and internal malignancies, specifically colorectal carcinoma (CRC), and can be related to mismatch-repair (MMR)-protein deficiency. In CRC context, p16-negativity in MLH1-deficient cases may denote methylation rather than mutation. The prime aim of this study was to evaluate the mismatch-repair (MMR)-protein deficiency and the p16 status among sebaceous neoplasms.

MATERIAL AND METHOD

From January 1990 through October 2012, 26 sebaceous adenomas (SAs) and 6 sebaceous carcinomas (SCs) were accrued. The expression of MLH1, MSH2, MSH6, and PMS2 was recorded. MLH1-deficient cases were tested for p16 status.

RESULTS

Eighteen (56%) of the 32 specimens with SA or SC displayed MMR-protein deficiency, comprising 17 (65.4%) SAs (MSH2/MSH6 loss in 12, MLH1/PMS2 loss in 3, MSH6 loss only in 2 cases) and 1 (16.7%) SC (MLH1/PMS2 loss). All 4 MLH1 deficient cases were p16-positive.

CONCLUSION

A substantial proportion of sebaceous neoplasms were MMR-protein deficient and thus likely MTS candidates. Given the low prevalence of sebaceous neoplasms in Denmark, immunohistochemistry for the four MMR-proteins is recommended in the initial diagnostic approach. The addition of p16 was none-informative, but evaluation of its utility in larger series is warranted.

Extraocular well-differentiated sebaceous tumors with overlying cutaneous horns: four tumors in three patients

BACKGROUND

Sebaceous tumors are adnexal neoplasms showing sebocytic differentiation. They range from benign to malignant and are associated with Muir-Torre syndrome (MTS). Several clinical and histopathological features associated with MTS have been described. Sebaceous tumors with an overlying cutaneous horn are extremely rare.

METHODS

Hematoxylin and eosin-stained slides were retrospectively reviewed to identify sebaceous tumors with marked hyperkeratosis, a condition that is often associated with cutaneous horns. Clinical correlation and mismatch repair protein immunohistochemical studies were then conducted.

RESULTS

Four tumors from three patients were identified in our archive. Three were classified as sebaceous adenomas, and the fourth was considered as a borderline sebaceous tumor favoring well-differentiated sebaceous carcinoma. All cases showed loss of expression of mismatch repair proteins (three tumors from two patients exhibited lost expression of MSH2 and MSH6, and the fourth exhibited lost expression of MLH1 and PMS2). Additionally, one patient presented characteristic clinical manifestations of MTS, including multiple sebaceous adenomas and visceral carcinomas.

CONCLUSIONS

We suggest that extraocular well-differentiated sebaceous neoplasms with overlying cutaneous horns may be an indication of underlying mismatch repair protein deficiency and potential MTS. This distinctive morphology might be an exaggerated combination of other features associated with MTS, i.e. keratoacanthoma-like architecture and extensive holocrine secretion.

DNA mismatch repair defects and microsatellite instability status in periocular sebaceous carcinoma

PURPOSE

To characterize mismatch repair protein expression and the role of DNA repair abnormalities in sebaceous carcinomas of the ocular adnexa.

DESIGN

Retrospective case-series study.

METHODS

We reviewed 10 cases of sporadic sebaceous carcinoma and 1 case involving a patient with a family history consistent with Muir-Torre syndrome. Immunohistochemistry was used to analyze the presence of 4 mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2) in these tumors. DNA was extracted from 7 of the larger tumors as well as from adjacent normal control tissue and microsatellite instability (MSI) analysis using 5 highly sensitive mononucleotides and 2 pentanucleotides was performed.

RESULTS

All 10 sporadic periocular sebaceous carcinomas maintained strong staining of the 4 mismatch repair genes, while tumor from the patient with Muir-Torre syndrome showed loss of staining for the mismatch repair genes MSH2 and MSH6. MSI testing of 7 tumors identified no changes in sporadic cases and yielded results supporting presence of repeat sequence instability in the Muir-Torre-associated case.

CONCLUSIONS

Sporadic sebaceous carcinoma of the ocular adnexa is not commonly associated with a loss of mismatch repair genes or microsatellite instability.

Mismatch repair protein deficiency is common in sebaceous neoplasms and suggests the importance of screening for Lynch syndrome

The association between Lynch syndrome and sebaceous neoplasms is well characterized. The absence of expression of mismatch repair proteins (MMRPs) by immunohistochemistry (IHC) is often used in other Lynch-associated tumors to guide testing. IHC for MLH1, PMS2, MSH2, and MSH6 was performed on 36 benign and malignant sebaceous neoplasms with the absence of one or more MMRP in 38.9% of cases. Among lesions with abnormal IHC, 71.4% were missing both MSH2 and MSH6, 21.4% lacked MLH1 and PMS2, and 7.1% lacked only MSH6. Of the 10 patients with absent MMRP, 5 had gene-test confirmed Lynch syndrome, 3 had no suggestive personal or family medical history and 2 had no recorded data. Tumor-infiltrating lymphocytes in neoplasms with absent MMRP were statistically significantly greater than in those with intact MMRP (16.5 vs. 9.7, P = 0.027). MMRP deficiency is common in sebaceous neoplasms, suggesting the importance of screening for Lynch syndrome in these patients.

10 rare tumors that warrant a genetics referral

The number of described cancer susceptibility syndromes continues to grow, as does our knowledge on how to manage these syndromes with the aim of early detection and cancer prevention. Oncologists now have greater responsibility to recognize patterns of cancer that warrant referral for a genetics consultation. While some patterns of common cancers are easy to recognize as related to hereditary cancer syndromes, there are a number of rare tumors that are highly associated with cancer syndromes yet are often overlooked given their infrequency. We present a review of ten rare tumors that are strongly associated with hereditary cancer predisposition syndromes: adrenocortical carcinoma, carcinoid tumors, diffuse gastric cancer, fallopian tube/primary peritoneal cancer, leiomyosarcoma, medullary thyroid cancer, paraganglioma/pheochromocytoma, renal cell carcinoma of chromophobe, hybrid oncocytoic, or oncocytoma histology, sebaceous carcinoma, and sex cord tumors with annular tubules. This review will serve as a guide for oncologists to assist in the recognition of rare tumors that warrant referral for a genetic consultation.

Immunohistochemistry with a mutation-specific monoclonal antibody as a screening tool for the BRAFV600E mutational status in primary cutaneous malignant melanoma

The V600E mutation of BRAF has emerged as both an effective biomarker and therapeutic target for select benign and malignant cutaneous and non-cutaneous human tumors and is typically determined using DNA-based techniques that include allele-specific PCR and direct DNA sequencing. Recently however, the development of new antibodies directed against the V600E protein has opened the door for an easier and more efficient strategy for identifying this mutation. Our present aim was to determine the efficacy of one such antibody, anti-B-Raf (V600E), a mouse monoclonal antibody in which the immunogen is a synthetic peptide derived from the internal region of BRAFV600E. A total of 35 cases of primary cutaneous melanoma were evaluated using a combination of DNA-based techniques that included allele-specific PCR and/or direct DNA sequencing and immunohistochemistry. Cases of papillary thyroid carcinomas (n=5) and colorectal carcinomas (n=5), known to harbor the BRAFV600E mutation, served as positive controls for the study. DNA analyses revealed that 6 of 35 (17%) cases of the primary cutaneous malignant melanoma possessed the BRAFV600E mutation. For immunohistochemical analyses, cytoplasmic positivity with anti-B-Raf was noted in 7 of 35 (20%) cases of primary melanoma and in all 10 positive controls. Statistical analyses of the data demonstrated that the sensitivity of the immunohistochemistry was 100% and specificity was 97%. Findings from the current study support the potential use of immunohistochemistry as an ancillary screening tool to assess the BRAFV600E mutation status in primary cutaneous melanoma.

Hepatocellular carcinoma as extracolonic manifestation of Lynch syndrome indicates SEC63 as potential target gene in hepatocarcinogenesis

OBJECTIVE

Lynch syndrome is a cancer predisposition syndrome caused by germline mutations in DNA mismatch repair (MMR) genes with microsatellite instability (MSI) as its molecular hallmark. Hepatocellular carcinoma (HCC) has not been considered part of the tumor spectrum. The aim was to provide a detailed molecular characterization of an HCC associated with Lynch Syndrome (Muir-Torre variant).

MATERIALS AND METHODS

HCC samples were analyzed for MSI, MMR protein expression and coding microsatellite instability (cMSI). Since cMSI also affected SEC63 coding for an endoplasmic reticulum membrane protein with implications for intracellular protein translocation, its impact on hepatocyte growth control was assessed in an established short-term model. Recombinant inbred mouse lines (BXD) showing different basal SEC63 expression levels were treated with the chemocarcinogen diethylnitrosamine (DEN) intraperitoneally. Proliferation and apoptosis of hepatocytes were determined after 48 h using Ki67 and TUNEL assays.

RESULTS

The HCC was high-grade microsatellite unstable with loss of MSH2 expression. cMSI was detected in four genes (ASTE1, SEC63, TAF1B, TGFBR2). However, only TGFBR2 is known to be involved in hepatocarcinogenesis. When investigating the impact of SEC63 expression on hepatocyte growth control in the murine model, low hepatic expression correlated significantly (p < 0.05) with a decrease in apoptosis and increased proliferative activity.

CONCLUSIONS

For the first time, an HCC with characteristic molecular features of association with Lynch syndrome is described. The pro-carcinogenic growth behavior of hepatocytes with low SEC63 expression in the murine model indicates a potential role for SEC63 in hepatocarcinogenesis in general, but this needs further functional validation.

Screening for Muir-Torre syndrome using mismatch repair protein immunohistochemistry of sebaceous neoplasms

Screening for the Muir-Torre variant of Lynch Syndrome (LS) using Mismatch Repair (MMR) gene immunohistochemistry (IHC) on sebaceous neoplasms (SNs) is technically feasible. To date, research into the clinical utility of MMR IHC for this indication is limited. We conducted a retrospective chart review of 90 patients with MMR IHC completed on at least one SN from January 2005 to May 2010. SNs included were adenomas, epitheliomas, carcinomas and basal and squamous cell carcinomas with sebaceous differentiation. Of the 90 patients, 13 (14 %) had genetically confirmed or fulfilled clinical criteria for a diagnosis of MTS and 51 patients (57 %) presented with an abnormal MMR IHC result (loss of one or more MMR proteins) on at least one SN. Abnormal IHC had a sensitivity of 85 %, specificity of 48 %, positive predictive value (PPV) of 22 % and negative predictive value (NPV) of 95 % when evaluating for MTS. When personal or family history of colorectal cancer (≥2 family members with a history of colorectal cancer) was taken into consideration, ignoring IHC results, sensitivity was 92 %, specificity was 99 %, PPV was 92 % and NPV was 99 %. MMR IHC on SNs when used to screen for MTS has poor diagnostic utility. We recommend that MMR IHC not be performed routinely on SNs when the patient does not have either personal or family history of colorectal cancer.

Dermatology clinics: what's new in dermatopathology: news in nonmelanocytic neoplasia

This article reviews the recent dermatopathology literature involving nonmelanocytic neoplasia, with a focus on important work done over the last 5 years. The discussion includes advances in the understanding of Merkel cell carcinoma pathogenesis and prognosis; changes in the seventh edition of the American Joint Committee of Cancer staging manual in reference to staging of squamous cell carcinoma and Merkel cell carcinoma; newly described or rare histopathologic patterns and entities including squamoid eccrine ductal carcinoma, rippled-pattern adnexal neoplasms, onychomatricoma, spindle cell predominant trichodiscoma/neurofollicular hamartoma, and myoepithelioma; and microsatellite instability in sebaceous neoplasms of Muir-Torre syndrome and other tumors.

p53 staining correlates with tumor type and location in sebaceous neoplasms

Sebaceous neoplasms are commonly considered in their relationship to the Muir-Torre syndrome and the now well-documented loss of DNA mismatch repair proteins leading to microsatellite instability. However, sebaceous neoplasms showing microsatellite instability comprise only a subset of this group of tumors, and thus, alternative tumorigenic mechanisms must exist. This article explores the relationship of p53, a tumor suppressor implicated in other cutaneous malignancies, and sebaceous neoplasia. We examined 94 sebaceous tumors from 92 patients. Tumors with strong nuclear p53 staining were significantly associated with the diagnosis of sebaceous carcinoma compared with benign sebaceous lesions, most notably for periocular carcinomas. Importantly, nuclear mismatch repair protein expression was intact in all lesions showing p53 alterations, suggesting that p53 dysfunction may represent a divergent pathway in the molecular pathogenesis of these tumors.

Role of immunohistochemistry in diagnosing tumors of cutaneous appendages

In recent years, there has been significant progress in immunohistochemistry as an ancillary tool in diagnostic dermatopathology. In most instances, the histologic diagnosis can be rendered with the routine histologic sections; however, immunohistochemistry can help to narrow the differential in diagnosing neoplasms of cutaneous appendages in some settings including adnexal versus epidermal origin, benign versus malignant adnexal neoplasms, and primary adnexal carcinoma versus cutaneous metastases as outlined in this review.

Muir-Torre syndrome: Facts and controversies

The cutaneous presentation of a tumor sometimes has implications for a patient and his or her family, and Muir-Torre syndrome is an example of this. Because a single skin lesion can have broad consequences, it is important for clinicians to be aware of Muir-Torre syndrome. The definition, potential clues, the role of ancillary testing (microsatellite, immunohistochemical, and genetic), and screening recommendations are reviewed.

Hereditary colon cancer: lynch syndrome

Lynch syndrome is the most common familial colorectal cancer syndrome. It is linked to germline mutations in one of four DNA mismatch repair (MMR) genes. A comprehensive family history is one important way to identify at-risk individuals. The elucidation of the molecular genetics of this syndrome has made it possible to screen for the disorder with molecular tests. Microsatellite instability and/or immunohistochemistry followed by germline testing for mutations in MMR genes is now a standard approach for clinically suspected cases. Correctly recognizing Lynch syndrome is essential for the application of appropriate screening and surveillance measures. Close surveillance and risk-reducing operations can decrease cancer-related mortality. In addition, counseling is an important component of the management of any family with Lynch syndrome.

Sebaceous neoplasia and the Muir-Torre syndrome: important connections with clinical implications

Sebaceous neoplasia comprises a spectrum ranging from benign to malignant. Proper histological identification is important for treatment, prognosis and potential association with the Muir-Torre syndrome (MTS). Our increased understanding of the significance and pathogenesis of these tumours has led to improved risk stratification, screening recommendations, and treatment of patients with an initial presentation of a sebaceous tumour. This review focuses on the diagnostic and histological features of sebaceous lesions, the MTS, and recent insights into the molecular pathogenesis of sebaceous tumours.

Pigmented lesion pathology: what you should expect from your pathologist, and what your pathologist should expect from you

The first part of this review examines the reliability of histologic diagnosis in pigmented lesions, as measured by concordance studies and medicolegal analysis. It emphasizes the role of clinicians in maximizing that reliability, by providing adequate clinical descriptions, using appropriate biopsy technique, and critically interpreting pathology reports. It identifies those entities that are especially problematic, either because they cannot be reliably recognized by the histopathologist or because their histology is a poor guide to their biologic behavior. The second part of the review is a guide to some of the more difficult and controversial pigmented lesions, including dysplastic nevus, spitzoid nevi and melanomas, cellular blue nevus, animal-type melanoma, and deep penetrating nevus.

Epidermal growth factor receptor (EGFR) expression in periocular and extraocular sebaceous carcinoma

Sebaceous carcinoma has a predominant periocular origin but can also be extraocular. These two groups have distinct clinical courses. Insight into the molecular determinants of tumorigenesis and metastasis is limited. There is no effective treatment for metastatic sebaceous carcinoma. Epidermal growth factor receptor (EGFR) is implicated in tumorigenesis and can be a therapeutic target in certain settings. We evaluated EGFR levels by immunohistochemistry (IHC), comparing its expression between periocular and extraocular tumors and assessed EGFR mutation status. IHC was performed in 36 cases: 19 periocular and 17 extraocular (10 associated with Muir-Torre syndrome-MTS). EGFR IHC was scored for percentage of positive cells (< 5%, 5-25%, 26-50%, > 50%) and intensity (+1 = low , +2 = moderate , +3 = high ). Extraocular carcinomas showed markedly increased levels of EGFR when compared to periocular carcinoma cases, both in terms of distribution (88% were > 25% of tumor cells vs. 16%) and intensity (77% were 2+ or 3+ vs. 21%) (p < 0.001). Among extraocular cases, there was significantly lower EGFR expression in MTS-related cases (p < 0.05). No EGFR mutations were identified. Our results underscore the divergent mechanisms underlying the tumorigenesis of periocular and extraocular sebaceous carcinoma and suggest an association between aggressive behavior and increased EGFR expression in extraocular sebaceous carcinoma.

Immunohistochemistry in the diagnosis of cutaneous neoplasms

In recent years, there has been a significant increase in the number of diagnostic immunohistochemical stains available to pathologists and dermatopathologists. Immunohistochemistry has become an indispensable tool in dermatopathology, not only in diagnosis but also in the treatment and prognostication of cutaneous neoplasms. In this review we attempt to outline current, as well as new, immunohistochemical stains of relevance in the diagnosis and classification of cutaneous neoplasms.

Sebaceous lesions and their associated syndromes: part II

Sebaceous lesions are associated with two syndromes with widespread multisystem disorders and tumors. Linear sebaceous nevus syndrome has been traditionally known as the triad of sebaceous nevus of Jadassohn, seizures, and mental retardation. This syndrome encompasses a much broader spectrum of multisystem disorders, which is explored below. Muir-Torre syndrome is described as the presence of sebaceous tumors or keratoacanthomas with an underlying visceral malignancy. It is caused by mutations in DNA mismatch repair genes. We discuss its relationship with Lynch syndrome and suggest a comprehensive algorithm on how to screen patients with sebaceous neoplasms for Muire-Torre syndrome. We also provide suggested intensive cancer screening guidelines based on recommendations for patients with Lynch syndrome that may also be of value for patients with Muir-Torre syndrome.

Cutaneous sebaceous neoplasms as markers of Muir-Torre syndrome: a diagnostic algorithm

Sebaceous gland neoplasms such as adenoma, epithelioma, and carcinoma are uncommon cutaneous tumors. Although sporadic, their occurrence is clinically significant because of their association with Muir-Torre syndrome (MTS). MTS is a rare autosomal dominant genodermatosis characterized by the occurrence of sebaceous gland neoplasms and/or keratoacanthomas associated with visceral malignancies that include gastrointestinal and genitourinary cancers. MTS is usually the result of germline mutation in one or more of the DNA mismatch repair (MMR) genes. MMR genes commonly implicated include MSH-2 and MLH-1 and, more recently, MSH-6. Recent evidence suggests that immunohistochemistry is very sensitive and effective in detecting these defects in cutaneous tumors in MTS. In addition, the genetic instability of cutaneous and visceral tumors in MTS caused by the defects in MMR genes can also be detected, using polymerase chain reaction (PCR)-based techniques, for microsatellite instability (MSI). Given that some sebaceous neoplasms represent cutaneous markers of MTS, what should we as dermatopathologists be advocating? Should we be looking for absence/loss of MMRs in all sebaceous neoplasms? When should we recommend assaying for MSI? This review attempts to address all of these issues with a view to streamlining the work-up of a patient presenting for the first time with a sebaceous neoplasm and no prior personal or family history of internal malignancies.

Dermatologic manifestations of colonic disorders

PURPOSE OF REVIEW

The skin is often a mirror for matters of internal diseases including disorders of the gastrointestinal tract. Here we enumerate many cutaneous and gastrointestinal associations and focus closely on three of the lesser known cutaneous manifestations of colonic disorders.

RECENT FINDINGS

Muir-Torre syndrome involves cutaneous sebaceous adenomas and internal malignancy; screening of cutaneous lesions for microsatellite instability, and absence of mismatch repair genes provides an opportunity for diagnosis of the syndrome. Degos' disease is a vasoocclusive disorder involving the cutaneous and gastrointestinal systems; this disease affects all ages with significant mortality, yet a benign variant only affecting the skin is described. Anecdotally reported treatments are listed. Metastatic Crohn's disease is the development of noncaseating granulomas at skin sites not contiguous with the gastrointestinal tract; cutaneous lesions may precede the onset of colonic disease or appear in the absence of active bowel disease, and extensive surgical debridement of perineal lesions is often necessary.

SUMMARY

Knowledge of these cutaneous manifestations provides an insight into the state of colonic health. These clues alert the clinician to the potential for life-threatening consequences, which leads to vigilant screening and hopefully earlier diagnosis.